The Megalodon shark was a prehistoric shark that lived from about 25 million years ago to approximately 1.5 million years ago.
This shark species has become increasingly popular because the Discovery Channel airs programs that claim it could still exist.
Two such programs are set to air on Friday night for four hours, starting at 8 p.m. EDT.
Many scientists say that the shark species definitely exist, while many deride Discovery for airing such programs.
When it was alive, Megalodons were the largest sharks to have ever lived and had a fearsome appetite, according to the Florida Museum of Natural History. By some estimates, Megalodons ate about 2,500 pounds of food every day, including fish and whales.
Fossils show that the sharks could have ingested several humans at the same time.
The sharks had 46 front row teeth, 24 in the upper jaw and 22 in the lower jaw. Most sharks have at least six rows of teeth, and a Megalodon had about 276 teeth at any given time.
In this photo taken May 6, 2010, University of Florida vertebrate paleontology graduate student Dana Ehret compares the size of a juvenile megalodon tooth from the Gatun Formation, Panama, left, with an adult megalodon tooth from Florida. (Jeff Gage/Florida Museum of Natural History)
A tooth of an extinct giant shark called ‘Carcharodon megalodon’ found by paleontologists during a project to recover fossils during the Panama Canal expansion, is displayed after a news conference in Panama City, Friday, April 26, 2013. (AP Photo/Arnulfo Franco)
Size comparison of Carcharodon carcharias (Great White Shark, 6m), Rhincodon typus (Whale Shark, 12m) and conservative/maximum estimates of the largest known adult size of Carcharodon megalodon (16-20m), with a human Homo sapiens. (Matt Martyniuk/Wikimedia Commons)
This animation from the Discovery Channel illustrated what a megalodon shark would have looked like when alive.
This picture shows a giant Carcharodon Megalodon shark jaw before being sold during an auction at Christie’s house in Paris on April 7, 2009, as part of a collection of prehistoric fossils. (AFP/Getty Images)
The sharks could grow 60 to 70 feet in length and up to 77 tons in weight, according to the Smithsonian Institution.
And how did they become extinct?
“It is believed that during the rapid climate change of the Ice Age, there was a dramatic reduction in the number of large whales that Megalodon fed upon,” according to the Florida museum. “This, along with competition from other predators (sharks) eventually led to the demise of the Megalodon.”
“When this shark lived, the world was forming into the one we now recognize—the Himalayas and Rockies were growing, the Isthmus of Panama rose from the sea to separate the Atlantic and Pacific, then massive glaciation locked much of the world’s water in ice,” added the Smithsonian.
“Everything was changing for the big sharks, possibly including what they ate and where they raised their kids, and they just couldn’t survive in the new world.” It notes that “Rumors of megalodon’s survival persist on the Internet, but no live specimen, or even fresh teeth, has ever been found, making it pretty unlikely that this shark still exists.”
Researchers have found tooth fossils over the years, which have been put on display at various museums, in addition to the enormous jaw fossils.
Researchers from the Florida museum discovered a 10-million-year-old nursery area for Megalodons in Panama, and found many of the shark species’ big, sharp teeth at the site.